How do you prepare and administer a vasopressin infusion in an Intensive Care Unit (ICU) setting?

Vasopressin Infusion Preparation and Administration in the ICU

For septic shock, prepare vasopressin by diluting 20 units/mL in normal saline or D5W, start at 0.01 units/minute, and titrate up by 0.005 units/minute every 10-15 minutes to a maximum of 0.03-0.04 units/minute as a second-line agent after norepinephrine. 1, 2

Preparation Protocol

Standard Dilution

• Dilute vasopressin injection (20 units/mL) in normal saline (0.9% sodium chloride) or 5% dextrose in water (D5W) prior to intravenous administration 1
• Discard unused diluted solution after 18 hours at room temperature or 24 hours under refrigeration 1
• Inspect the solution for particulate matter and discoloration before use 1

Administration Guidelines

Initial Dosing by Indication

• Septic shock: Start at 0.01 units/minute 1
• Post-cardiotomy shock: Start at 0.03 units/minute 1
• Titrate up by 0.005 units/minute at 10-15 minute intervals until target blood pressure (MAP ≥65 mmHg) is reached 1, 2

Maximum Dosing

• Limited data exists for doses above 0.07 units/minute for septic shock 1
• For post-cardiotomy shock, limited data above 0.1 units/minute 1
• Adverse reactions are expected to increase with higher doses 1
• The Society of Critical Care Medicine recommends a standard dose of 0.03 units/minute when added to norepinephrine, with doses higher than 0.03-0.04 units/minute reserved for salvage therapy only 2

Critical Clinical Context

When to Initiate Vasopressin

• Vasopressin should NEVER be used as the sole initial vasopressor—it must be added to norepinephrine, not used as monotherapy 2
• Add vasopressin when norepinephrine requirements remain elevated (typically at 0.1-0.2 mcg/kg/min) or when you need to decrease norepinephrine dosage while maintaining MAP target of 65 mmHg 2, 3
• In perioperative anaphylaxis with persistent hypotension after 10 minutes, vasopressin can be added as a bolus of 1-2 IU with or without infusion at 2 units/hour 3

Weaning Protocol

• After target blood pressure has been maintained for 8 hours without the use of catecholamines, taper vasopressin by 0.005 units/minute every hour as tolerated to maintain target blood pressure 1
• Once vasopressin is added, you can either raise MAP to target OR decrease norepinephrine dosage while maintaining hemodynamic stability 2

Monitoring Requirements

Essential Monitoring

• Continuous arterial blood pressure monitoring via arterial catheter is recommended for all patients requiring vasopressors 2
• Monitor for signs of excessive vasoconstriction: digital ischemia, decreased urine output, rising lactate, or worsening organ dysfunction 2
• Watch for adverse effects including decreased cardiac output, decreased heart rate, arrhythmias, myocardial ischemia, mesenteric ischemia, and digital ischemia 4

Fluid Resuscitation Requirements

• Adequate fluid resuscitation (minimum 30 mL/kg crystalloid) should precede or accompany vasopressor therapy 3, 2
• In maternal sepsis, the Society for Maternal-Fetal Medicine recommends tailoring initial fluid resuscitation to the patient's condition, with 1-2 L initial bolus, increasing to 30 mL/kg within first 3 hours for septic shock 3

Common Pitfalls to Avoid

• Do not titrate vasopressin as a single vasopressor agent—it should be maintained at a fixed low dose (0.01-0.04 units/minute) while adjusting norepinephrine 5
• Do not use vasopressin before ensuring adequate volume resuscitation, as vasoconstriction in hypovolemic patients causes severe organ hypoperfusion 2
• If norepinephrine requirements remain high despite vasopressin addition, consider adding epinephrine as a third agent rather than increasing vasopressin beyond 0.03-0.04 units/minute 2
• In hypodynamic sepsis models, vasopressin can compromise oxygen delivery and decrease systemic and gut blood flow, so use with caution in patients with low cardiac output 5

Special Considerations for Variceal Hemorrhage

For gastroesophageal variceal hemorrhage in cirrhosis, a different vasopressin protocol applies:

• Administer continuous IV infusion of 0.2-0.4 units/minute, which can be increased to a maximal dose of 0.8 units/minute 3
• Must always be accompanied by IV nitroglycerin at a starting dose of 40 µg/minute (maximum 400 µg/minute), adjusted to maintain systolic blood pressure of 90 mmHg 3
• Can only be used continuously at the highest effective dose for a maximum of 24 hours to minimize side effects 3